Roof curb structures and methods of manufacture

Abstract

Roof curb structures include side shells made by cutting a series of transversely aligned V-shaped notches and straight slots along top and bottom edges of a continuous length of sheet metal strip material at spaced apart intervals corresponding to the length of each side of the side shells to be formed therefrom. Then the strip material is cut to length corresponding to the length of one, two or four sides of the side shells and the top and bottom edges are roll formed in opposite directions to form oppositely extending top and bottom flanges. Next the severed lengths of strip material are folded at each transversely aligned intermediate notch and slot (if the length is greater than the length of one of the sides) to form continuous right angle corners at such intermediate notches and slots, and the ends of such strip material are either seam welded together or the ends of additional lengths of strip material are fitted and seam welded together to form box-like shells having inturned top flanges and outturned bottom flanges. Then the outturned bottom flanges of the shells are positioned against four identical bottom strips that extend a substantial portion of the length of the outturned bottom flanges and beyond one end into underlying relation to an end of the next adjacent outturned bottom flange, and the outturned bottom flanges and the next adjacent outturned bottom flange are spot welded to the same bottom strips to form rigid bottom supports for the shells.

What is claimed is: 
     
       1. A roof curb structure for mounting a ventilator on a roof penetration of a building comprising a sheet metal shell having a generally box-like shape including four sides having outturned bottom flanges, and a bottom support comprised of four sheet metal bottom strips underlying a substantial portion of the length of said bottom flanges and protruding beyond one end of said bottom flanges into underlying relation to an end of the next adjacent bottom flange, said bottom flanges and the end of the next adjacent bottom flange being secured to the same bottom strips. 
     
     
       2. The roof curb structure of claim 1 wherein said outturned bottom flanges and said bottom strips are welded together. 
     
     
       3. The roof curb structure of claim 1 wherein said sides have inturned top flanges with beveled ends that butt up against the ends of adjacent inturned top flanges. 
     
     
       4. The roof curb structure of claim 3 wherein innermost edges of said inturned top flanges have downturned lips in substantial vertical alignment with upturned lips on innermost edges of said bottom strips. 
     
     
       5. The roof curb structure of claim 4 wherein said upturned lips on said bottom strips have a length substantially corresponding to the length of said downturned lips. 
     
     
       6. The roof curb structure of claim 1 wherein said bottom flanges have squared off ends, and said bottom strips have a length substantially equal to or greater than the length of said bottom flanges. 
     
     
       7. The roof curb structure of claim 6 wherein the protruding portions of said bottom strips are butted up against or overlie the ends of the next adjacent bottom strips. 
     
     
       8. The roof curb structure of claim 1 wherein said shell consists of a single piece of sheet metal having four continuous sides interconnected by three continuous corners and one seam welded corner. 
     
     
       9. The roof curb structure of claim 1 wherein said shell consists of two separate pieces of sheet metal, each having two continuous sides interconnected by continuous corners and two seam welded corners. 
     
     
       10. The roof curb structure of claim 1 wherein said shell consists of four separate pieces of sheet metal each forming a side of said shell, said sides being joined together at their ends by four seam welded corners. 
     
     
       11. The roof curb structure of claim 1 further comprising a damper tray consisting of four damper tray strips each having a length substantially equal to the interior spacing between opposed upturned lips on said bottom strips less the width of said damper tray strips, said damper tray strips having upturned lips along outer edges of said damper tray strips in mating engagement with said upturned lips on said bottom strips, said damper tray strips having one end in abutting engagement with said upturned lips on said bottom strips, and an other end butting up against an inner edge of the next adjacent damper tray strip, said upturned lips on said damper tray strips being secured to said upturned lips on said bottom strips. 
     
     
       12. The roof curb structure of claim 11 wherein said upturned lips on said damper tray strips and said bottom strips are spot welded together. 
     
     
       13. The roof curb structure of claim 1 further comprising insulation material extending around the inner periphery of said shell between inturned top flanges on said shell and inner portions of said bottom strips and retained therebetween by vertically aligned downturned and upturned lips on inner edges of said inturned top flanges and said inner portions of said bottom strips, respectively. 
     
     
       14. The roof curb structure of claim 1 wherein said sides have inturned top flanges, and wood nailers are attached to top surfaces of said inturned top flanges around the entire periphery of said shell. 
     
     
       15. A roof curb structure for mounting a ventilator on a roof penetration of a building comprising a one piece, box-like sheet metal shell having four continuous sides interconnected together by three continuous corners and one seam welded corner, said sides having outturned bottom flanges and inturned top flanges, said inturned top flanges having beveled ends in abutting engagement with the beveled ends of adjacent inturned top flanges. 
     
     
       16. A roof curb structure for mounting a ventilator on a roof penetration of a building comprising a shell having a generally box-like shape, said shell being formed from two separate pieces of sheet metal each having two continuous sides interconnected by continuous right angle corners, said separate pieces of sheet metal having opposite ends joined together at two seam welded corners, said sides having outturned bottom flanges and inturned top flanges, said inturned top flanges having beveled ends in abutting engagement with the beveled ends of adjacent inturned top flanges. 
     
     
       17. A method of making roof curb structures for supporting ventilators on roofs of buildings comprising the steps of: (a) cutting a series of transversely aligned V-shaped notches and straight slots along top and bottom edges of a continuous length of sheet metal strip material at spaced apart intervals corresponding to the length of each side of box-like shells to be formed from the strip material,   (b) transversely severing the strip material at every fourth aligned notch and slot,   (c) roll forming the top and bottom edges of each severed length of strip material in opposite directions at the full depth of the notches and slots to form oppositely extending top and bottom flanges along such top and bottom edges,   (d) forming each severed length of strip material at each transversely aligned notch and slot intermediate the ends of each severed length of strip material in the direction of the top flanges to bring the edges of the intermediate notches into abutting engagement with each other to form three continuous right angle corners and bring the ends of each severed length of strip material into engagement with each other to form one non-continuous right angle corner, and   (e) seam welding the non-continuous corner of each severed length of strip material to form a box-like shell for such roof curb structures having four sides with inturned top flanges along the top edges, and outturned bottom flanges along the bottom edges.   
     
     
       18. The method of claim 17 further comprising the steps of attaching the outturned bottom flanges of each shell to outer portions of four identical sheet metal bottom strips to form a bottom support for each shell, the bottom strips each having inner portions extending inwardly of the sides of each shell in vertically spaced relation to the inturned top flanges of each shell. 
     
     
       19. The method of claim 18 wherein the bottom strips extend a substantial portion of the length of the outturned bottom flanges and beyond one end of the outturned bottom flanges into underlying relation to an end of the next adjacent outturned bottom flange, the outturned bottom flanges and the end of the next adjacent bottom flange being spot welded to the same bottom strips. 
     
     
       20. The method of claim 18 further comprising the steps of forming downturned lips on the innermost edges of the top flanges and upturned lips on the innermost edges of the bottom strips of the same length as the downturned lips, and positioning the upturned lips on the bottom strips in substantial vertical alignment with the downturned lips on the innermost edges of the top flanges. 
     
     
       21. The method of claim 20 further comprising the step of placing insulation material around the inner periphery of each shell between the top flanges and inner portions of the bottom strips inwardly of the downturned and upturned lips. 
     
     
       22. The method of claim 21 further comprising the step of attaching wood nailers to the top flanges around the entire periphery of each shell. 
     
     
       23. The method of claim 20 further comprising the steps of fitting four identical damper tray strips within a box-like opening formed by the upturned lips on the bottom strips with one end of each damper tray strip pressed up against a respective upturned lip at each corner and the other end of each damper tray strip butting up against an inner edge of the next adjacent damper tray strip, and spot welding upturned lips on the outer edges of the damper tray strips to the upturned lips on the bottom strips. 
     
     
       24. A method of making roof curb structures for supporting ventilators on roofs of buildings comprising the steps of: (a) cutting a series of transversely aligned V-shaped notches and straight slots along top and bottom edges of a continuous length of sheet metal strip material at spaced apart intervals corresponding to the length of each side of box-like shells to be made from the strip material,   (b) transversely severing the strip material at every second aligned notch and slot,   (c) roll forming the top and bottom edges of each severed length of strip material in opposite directions at the full depth of the notches and slots to form oppositely extending top and bottom flanges along the top and bottom edges,   (d) forming each severed length of strip material at each transversely aligned intermediate notch and slot in the direction of the top flanges to bring the edges of the intermediate notch into abutting engagement with each other to form a continuous right angle corner in each folded length of strip material,   (e) fitting the ends of two such folded lengths of strip material together to form two non-continuous right angle corners, and   (f) seam welding such non-continuous corners together to form a box-like shell for such roof curb structures having two continuous right angle corners and two seam welded right angle corners.